Home – Home – Jornals – Avtometriya 2014 number 1

The depth of two-dimensional plane images spaced apart along the visual axis of the eye for stimulating accommodation in 3D displays is considered. The diffraction depth of the plane images is determined, and it is demonstrated to increase with decreasing image resolution acuity.

This paper considers the effect of errors in the technological process using an optimized contour mask technique for fabricating piecewise continuous relief diffractive optical elements on the reduction in the backward slopes of diffraction zones and the increase in the diffraction efficiency of the elements. The process parameter tolerances necessary for the implementation of the method are within the parameters of the standard microelectronic processes and equipment. The proposed method can be useful for laser writing systems and projection lithography that form the relief in a photoresist with a backward slope width exceeding 1 µm since it provides a significant improvement in the performance of the fabricated diffraction structures.

A method is proposed for selecting an adaptive threshold for the detection of an interference signal in an optical profilometer based on estimation of optical quantum noise in interferograms of each measurement point. It is shown that when using differential interferograms, this approach allows extending the dynamic range of detection of interference and automate the process of measuring surface topography with a large variation in the light reflection coefficient in the measurement zone. Theoretical calculations, and results of calculations and experiments are presented.

Estimates are given of the power of the Kuiper and Watson goodness-of-fit tests and three Zhang tests with the Z_A, Z_C, and Z_K statistics with respect to some pairs of competing laws in testing simple and composite hypotheses. The powers of these tests are compared with the powers of the Kolmogorov, Cramer-von Mises-Smirnov, and Anderson-Darling tests. Statistic distribution models and tables of percentage points are constructed which allow the Kuiper and Watson goodness-of-fit tests to be used to test composite hypotheses about the goodness of fit of samples against various parametric distribution laws. An interactive simulation method is proposed that allows constructing and using distributions of test statistics in solving problems of statistical analysis.

One approach to finding suitable critical values of statistics of a new nonparametric statistical test previously proposed by the author for the problem of testing the hypothesis of homogeneity of two and three samples is considered. The Wilcoxon test is equivalent to a particular ("linear") case of the proposed test. A comparative analysis of these tests is performed for the case where the Wilcoxon test is locally the most powerful one among the ranking methods.

A passive bistatic radar comprising an illumination source and two antennas for receiving the direct signal from the illumination source and a mixture of signals scattered by moving objects is considered. The problem of estimating the amplitudes, delays, and Doppler shifts of scattered signals is formulated as the problem of minimizing the residual of an overdetermined system of linear algebraic equations. An additional condition is imposed on the unknown amplitude to provide sparsity of the desired signal amplitudes in the delay-Doppler shift coordinates. The problem is solved by the variational method.The method was successfully tested using real data.

Algorithms of filtration of trajectory points with the use of the Kalman filter and particle filter are studied from the viewpoint of object tracking in a seismic security system. A comparative analysis of the algorithms is performed in terms of the accuracy of determining the coordinates of the object trajectory points and computational complexity.

The use of the Bezier surface as a smoothing filter for vector fields is studied. Advantages of the Bezier surface over the moving average filter are determined. The algorithm of adaptation of the filter aperture size is modified. The efficiency of adaptation of the aperture size in vector field processing in the problem of estimating the material strain by the method of digital image correlation is considered.

Asymptotic properties of a nonparametric estimate of the two-dimensional probability density of independent random variables are studied. Based on these results, the dependence of its efficiency on data incompleteness in the initial statistical information is determined.

A revision of works on the methods of writing and apodization of fiber Bragg gratings (FBG) is presented. The possibilities of apodizing FBGs recorded by holographic methods with phase masks and Lloyd interferometer using laser radiation with a Gaussian intensity profile are considered. FBG reflection spectra are numerically simulated for different parameters of the writing beam and configurations of the experimental setup. Side-lobe suppression and FBG spectrum smoothing are experimentally demonstrated. It is shown that this effect is due to equalization of the average value of the induced refractive index in the FBGs. FBG applications, in particular, as frequency selectors in fiber lasers (tunable, narrow-band, and multiwavelength) are described.

Results of studying the possibilities of passivating InAs surfaces by ultrathin oxide films (~3 nm) in a glow-discharge plasma and producing tunnel MIS photodiodes on this basis are presented together with results of investigating the kinetics of oxidation and the chemical composition of oxide films formed. This is the first time when anhysteretic dependences of the capacitance on the bias are observed for InAs-based MIS structures at the liquid nitrogen temperature in a wide field range (from −7 · 10⁶ to +5 · 10⁶ V/cm). MIS structures are IR-photosensitive in the current mode. The estimated values of detectability are D^* = 2.6 · 10¹²-8.2 · 10¹² cm·Hz^1/2 · W⁻¹ and D^* = 1.5 · 10¹¹ cm · Hz^1/2 · W⁻¹ at temperatures of 78 and 198 K, respectively. The ampere-watt sensitivity value at a temperature of 78 K is 0.98 A/W, and the quantum efficiency is 0.43 (with no antireflecting coating of the InAs substrate and sapphire window).

Spectral dependences of quadratic nonlinear coefficients of new chromophore-containing polyimides with covalently attached DR13 chromophore molecules are synthesized and studied by the second-harmonic generation method in the fundamental radiation wavelength from 800 to 1400 nm. The obtained record values of quadratic nonlinear coefficients are 80 to 120 pm/V. Dispersions of refractive indices and extinction coefficients in the spectral range from 400 to 800 nm are determined by spectral ellipsometry, resulting in the improved accuracy of nonlinear coefficients.

An algorithmic approach and software for solving the problem of search for statistically significant overrepresented biological characteristics of genes from a given set are proposed. The problem is related to implementation of permutation (randomization) tests well known in biology. Parallel software based on the potential parallelization of the permutation test is developed and implemented on GPUs. The efficiency of application of this software on empirical materials is estimated.